I checked whether absolute accuracy produced by processing images together with gcp file having 5 GCP points has been improved or not, by comparing coordinates of GCP points on the “Orthophoto” on QGIS program with “Actual” coordinates measured by GPS station. These are comparison of 2 GCP points among 5 points:

I processed 100 images without gcp_list.txt file on WebODM and compared the coordinates of orthophoto generated with those of orthophoto produced from processing images with gcp_list file. The coordinates were same in both cases, which means gcp_list file didn’t improve absolute accuracy at all.

What is wrong with this? How can absolute accuracy be improved to survey grade?

Converted to UTM last night, re-ran it, and it was completed this morning. But you can see that the GCPs are not exactly on the spot.
It detected that the area was WGS1984 UTM Zone 12, so I used that coord system for the GCPs. (Which were collected with a Trimble GeoXH.) Shouldn’t the GCP coords match even if they were off due to GPS inaccuracies? All of the points are off by a few feet. I rechecked the pixel locations for the images and all are correct. Would using an EPSG code yield bet…

I do notice in the log that there are multiple “mean georeference error” messages, but I’m not sure that’s related.